The wintry clouds drop spangles on the mountains. If the thing occurred once in a century historians would chronicle and poets would sing of the event; but Nature, prodigal of beauty, rains down her hexagonal ice-stars year by year, forming layers yards in thickness. The summer sun thaws and partially consolidates the mass. Each winter's fall is covered by that of the ensuing one, and thus the snow layer of each year has to sustain an annually augmented weight. It is more and more compacted by the pressure, and ends by being converted into the ice of a true glacier, which stretches its frozen tongue far down beyond the limits of perpetual snow. The glaciers move, and through valleys they move like rivers.
— John Tyndall, 1861

Saturday, November 22, 2014

Earth might well have coalesced from cosmic dust and gas. Billions of years later, a thin raft surrounding Earth teems with co-dependent organisms.

The question of the origin of life is essentially speculative. We have to construct, by straightforward thinking on the basis of very few factual observations, a plausible and self-consistent picture of a process which must have occurred before any of the forms which are known to us in the fossil record could have existed.
— John Desmond Bernal

Where did the ingredients for the simplest unicellular life forms come from? Life's ingredients might have come from comets.

Early Earth was not very hospitable when it came to jump-starting life. In fact, new research shows that life on Earth may have come from out of this world.
― Astrobiology Magazine

Comets are vestiges from the formation of our solar system some 4.5 billion years ago. Comets that move into range of space travel, arrive well-preserved from the freeze locker of the outer solar system.

As it travels near the Sun and Earth, a disintegrating comet represents a treasure-trove of hard data about conditions present during the early stages of the solar system.

The composition of comets interests us because scientists posit that life-building organic compounds might have come from icy comets that collided with Earth millions of years ago.

Organic compounds form the basis of proteins and nucleobases (the building blocks of DNA and RNA). Oceans might have been formed from icy comets and asteroids crashing into Earth.

The first comet landing of a robotic spacecraft touched down on Comet 67P on November 12, 2014. Until then, our knowledge of comets came from a handful of flyby space missions

Saturday, November 15, 2014

Earth's crust has seven or eight plates that drift on a softer mantle. The motions of the plates is described by the universally accepted theory of plate tectonics. Plate tectonics extends a preceding theory of continental drift popular in the early to mid 20th century.

It must have appeared almost as improbable to the earlier geologists, that the laws of earthquakes should one day throw light on the origin of mountains, as it must to the first astronomers, that the fall of an apple should assist in explaining the motions of the moon.
— Charles Lyell, Principles of Geology (1830-3), Vol. 3, 5.

Interferometric synthetic aperture radar (InSAR) streams data to a satellite that records ground surface movements to within an inch. InSAR technology was first used to analyze the 1992 Landers earthquake.

InSAR has since provided data for variety of earthquakes including the M7.6 1999 Izmit earthquake that caused extensive damage and loss of life.

Surface motion caused by the Izmit earthquake is shown in the interferogram below which depicts surface changes. The interferogram used pairs of images from InSAR data recorded shortly before, and a month after, the earthquake event.

1999 Izmit, Turkey Earthquake Interferogram

Each color contour represents 1.1 inches (28 mm) of vertical displacement (toward the satellite), or 2.8 inches (70 mm) of horizontal movement. The thin, east-west red lines show the location of fault breaks. The thicker, east-west black lines show a fault rupture inferred from the data.

"Though the theories of plate tectonics now provide us with a modus operandi, they still seem to me to be a periodic phenomenon. Nothing is world-wide, but everything is episodic. In other words, the history of anyone part of the earth, like the life of a soldier, consists of long periods of boredom and short periods of terror."
— Derek Victor Ager, The Nature of the Stratigraphical Record, 3rd Ed. 1993, 141.

GPS

Another means to record earthquake-induced displacement is to use GPS. A marker bolt is drilled into the ground. The coordinates of the bolt are recorded using a GPS device. The coordinates of the bolt are recorded again at a later date to determine if movement has occurred. Consumer GPS devices are accurate to within several meters. Measuring earthquake movements requires a finer resolution GPS receiver that uses the phase of the signal to increase accuracy to within millimeters.

We take for granted all the constant, fixed things, and eventually stop paying any attention to them. At the same time we observe and obsess over small, fast-moving, ephemeral things of little value.

The trick to rediscovering constants is to stop and focus on the greater panorama around us. While everything else flits abut, the important things remain in place.

Their stillness appears as reverse motion to our perspective, as relativity resets our motion sensors. It reboots us, allowing us once again to perceive.

And now that we do see, suddenly we realize that those still things are not so motionless after all. They are simply gliding with slow individualistic grace against the backdrop of the immense universe.

Saturday, November 8, 2014

Waterfalls are formed when a river is young, but formation gradually occurs over several thousand years.

Rivers flow over strata of rock that vary in resistance to erosion. As rapid river flow scours a channel into a less erosion-resistant stratum below, it transports loose material downstream thus increasing the slope of the watercourse.

As the flowing water carries the softer rock downstream, the riverbed becomes steeper. Gradually the slope increases to the point where rapids become a waterfall.

As a plunge pool develops, turbulence and whirlpools in the water undercuts the soft rock.

Illustration by Jerry Crimson Mann

After a long period as a fully-formed waterfall, the hard rock overhang can slowly retreat upstream to form a river canyon as the hard rock is eventually eroded and carried downstream.

“When I was walking in the mountains with the Japanese man and began to hear the water, he said, 'What is the sound of the waterfall?' 'Silence,' he finally told me.”
― Jack Gilbert, Collected Poems

Selandjafoss, Icelandby Martin Meeks

Man is not himself only...He is all that he sees; all that flows to him from a thousand sources...He is the land, the lift of its mountain lines, the reach of its valleys.
― Mary Hunter Austin

Saturday, November 1, 2014

"When we try to pick out anything by itself, we find it hitched to everything else in the Universe."

Wolf Reintroduction, January 1995.

What-eats-what in the biosphere is a dynamic web where organisms are hitched. Consider the grey wolf.

Grey wolves were extirpated from Yellowstone by the mid-1920s. During the winters of 1995-96
wolves were re-introduced to the park after a 70-year absence.

This ecological tinkering has allowed scientists to study a textbook example of a trophic cascade.

Trophic cascades occur when a predator reduces the population of its prey. This population reduction cascades to release the next trophic level from predation. Grey wolves are apex predators. Grey wolves have gradually surpressed the population of elk in the park since their reintroduction.

The suppression of the elk population has enabled plant species like aspen, cottonwood, and willow to flourish. Scientists have observed the top-down impact of the grey wolf since its reintroduction in Yellowstone 15 years ago. The abundance and diversity of plant species have increased.

Aldo Leopold first described the concepts of trophic cascades after observing the overgrazing of mountain slopes following the extermination of wolves.

“We reached the old wolf in time to watch a fierce green fire dying in her eyes. I realized then, and have known ever since, that there was something new to me in those eyes – something known only to her and to the mountain. I was young then, and full of trigger-itch; I thought that because fewer wolves meant more deer, that no wolves would mean hunters’ paradise. But after seeing the green fire die, I sensed that neither the wolf nor the mountain agreed with such a view.”
― Aldo Leopold

Bottom-up cascades also occur. Changes in the abundance and diversity of plants will directly impact higher level predation and population.

“Only the mountain has lived long enough to listen objectively to the howl of the wolf.”
― Aldo Leopold

Wolves howling at the moon is a compelling myth. A howling wolf is a plaintive reminder of our existential connection to all living things. Seeing constellations in the night sky while wolves howl harkens us to consider our place in the cosmos. We are bound to a thin band of life that covers the Earth. Everything is hitched.